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November 1989

Comparison of the Antihypertensive Effects of Betaxolol and Chlorthalidone as Monotherapy and in Combination

Author Affiliations

From the Cardiovascular Center of Northern Virginia, Falls Church (Drs Burris and Mroczek); the Hypertension Research Center, Falls Church, Va (Dr Davidov); the Urban Cardiology Research Center, Baltimore, Md (Dr Jenkins); the Physician's Research Organization, Norristown, Pa (Dr Rofman); Harleysville (Pa) Medical Associates (Dr Ginsberg); Nephrology Associates, Lansing, Mich (Dr Rosenbaum); and the Clinical Research Center, New Orleans, La (Drs Ryan and Jain).

Arch Intern Med. 1989;149(11):2437-2441. doi:10.1001/archinte.1989.00390110039009

• In this multicenter, double-blind, parallel study, the antihypertensive effects of betaxolol (20 mg once daily) and/or chlorthalidone (25 mg once daily) were analyzed in 186 patients with essential hypertension. Following a 2- to 4-week placebo baseline period, patients were randomized to one of two treatment groups (betaxolol or chlorthalidone) and studied for 6 weeks while receiving single therapy and an additional 6 weeks with a combination of the two agents. Significant decreases from baseline supine diastolic blood pressure (SDBP) were observed in both groups at the end of the single-therapy phase (11 mm Hg in SDBP for betaxolol and 12 mm Hg in SDBP for chlorthalidone); a further significant decrease (7mm Hg for betaxolol and 8 mm Hg for chlorthalidone in SDBP) was observed from the end of the single-therapy phase to the end of the combination-therapy phase. Changes in supine systolic blood pressure (SSBP) from baseline to the end of the single-therapy phase were 10 mm Hg for the betaxolol and 16 mm Hg for the chlorthalidone group. In all cases, within-group changes were statistically significant. From the end of single therapy to end of combination therapy there was an additional 14–mm Hg and 13–mm Hg reduction in SSBP in the betaxolol and chlorthalidone groups, respectively. Overall, 89% of the randomized patients completed the single-treatment phase (phase I), and 89% of those patients completed the combined therapy phase (phase II). There was no significant difference between treatment groups in the clinical response rate (SDBP at or below 90 mm Hg or a decrease from baseline of at least 10 mm Hg). A substantial percentage of patients completing phase I responded to either single agent (58% for betaxolol and 65% for chlorthalidone). Among patients completing phase II therapy, the combination of the two agents produced a greater response rate (83% for the betaxolol-first group and 85% for the chlorthalidone-first group). In conclusion, both agents were effective and well tolerated. The most frequent adverse events in the single-therapy phase were headache, arthralgia, and dizziness, while bradycardia, rhinitis, arthralgia, and dizziness were most frequent in the combination-therapy phase. The combination of betaxolol (20 mg) and chlorthalidone (25 mg) once daily produced an additive antihypertensive effect regardless of which drug was administered first.

(Arch Intern Med. 1989;149:2437-2441)

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